java学习——比较器，进行排序

Arrays类

inttemp[] = {3,5,7,9,1,2,6,8};//声明一个整形数组

Arrays.sort(temp);//数组排序

System.out.println(Arrays.toString(temp));// 以字符串输出数组  [1, 2, 3, 5, 6, 7, 8, 9]

intpoint = Arrays.binarySearch(temp,3);// 检索数据位置

System.out.println("元素'3'的位置在："+ point);//元素'3'的位置在：2

Arrays.fill(temp,3);//填充数组

System.out.println(Arrays.toString(temp));// 以字符串输出数组 [3, 3, 3, 3, 3, 3, 3, 3]

Comparable接口   

public class Student implements Comparable {//指定类型为Student

private String name;

private int age;

private float score;

public Student(String name,int age,float score) {

this.name= name;

this.age= age;

this.score= score;

}

publicString toString() { 

returnname+"\t\t"+age+"\t\t"+score; 

}

@Override

public int compareTo(Student o) {// 覆写compareTo()方法，实现排序规则的应用

if(this.score> o.score) {

return -1;

}else if(this.score< o.score) {

return 1;

}else{

if(this.age> o.age){

return 1;

}else if(this.age< o.age){

return -1;

}else{

return 0;}}}}

main

Student stu[] = {new Student("张三",20,90.0f),new Student("李四",22,90.0f),new Student("王五",20,99.0f),new Student("赵六",20,70.0f),new Student("孙七",22,100.0f)};

java.util.Arrays.sort(stu);// 进行排序操作

for(int i =0; i < stu.length; i++) {

System.out.println(stu[i]);

}

//返回如下：

自定义比较规则：

//定义学生类

public classStudents {

privateStringname;

private intage;

publicStudents(String name,intage) {

this.name= name;

this.age= age;

}

public booleanequals(Object obj) {

if(this== obj){

return true;

}

if(!(objinstanceofStudents)){

return false;

}

Students stu = (Students) obj;

if(stu.name.equals(this.name)&&stu.age==this.age){

return true;

}else{

return false;

}

}

publicString toString() {

returnname+"\t\t"+age;

}

publicString getName() {

returnname;

}

public voidsetName(String name) {

this.name= name;

}

public intgetAge() {

returnage;

}

public voidsetAge(intage) {

this.age= age;

}

}

// 定义比较规则

public classStudentComparatorimplementsComparator {//实现比较器接口

@Override

public intcompare(Students s1, Students s2) {// 为学生类定义比较规则

if(s1.equals(s2)){

return0;

}else if(s1.getAge() < s2.getAge()){

return1;

}else{

return-1;

}

}

}

// 为对象数组排序

Students student[] = {new Students("张三",20),new Students("李四",22),new Students("王五",20),new Students("赵六",22)};

java.util.Arrays.sort(student,newStudentComparator());//排序，指定排序规则

for(inti =0; i < student.length; i++) {

System.out.println(student[i]);

}

//返回如下：